The present invention relates to a dispenser having an actuation indicating device for indicating the number of actuations thereof. In particular, the invention relates to metered dose inhalers by means of which medicaments contained in an aerosol container may be administered to a patient.
It is well known to treat patients with medicaments contained in an aerosol, for example, in bronchodilator therapy. It is also known to use for such therapy, medicaments which are contained in an aerosol and are administered to a patient by means of an inhalation device comprising a tubular housing or sleeve in which the aerosol container is located and an outlet tube leading out of the tubular housing. The aerosol containers used in such inhalation devices are designed to deliver a predetermined dose of medicament upon each actuation by means of an outlet valve member at one end which can be opened either by depressing the valve member while the container is held stationary or by depressing the container while the valve member is held stationary. In the use of such devices, the aerosol container is placed in the tubular housing with the outlet valve member of the container communicating via a support with the outlet tube, for example a nozzle or mouthpiece. When used for dispensing medicaments, for example in bronchodilation therapy, the housing is then held by the patient in a more or less upright condition and the mouthpiece or nozzle of the inhalation device is placed in the mouth or nose of the patient. The aerosol container is pressed towards the support to dispense a dose of medicament from the container which is then inhaled by the patient.
A problem arising from use of such known devices is that the patient cannot determine the amount of medicament in the container at any given time. In an extreme case this could mean that the patient, possibly suffering from severe bronchospasm and needing a dose of medicament, will find that the container will not dispense a dose because its contents have already been exhausted.
In solution to the above described problem there has been suggested the use of dose indicating devices, which typically count the number of doses delivered from or remaining in the aerosol container, thereby enabling the patient to determine how much medicament is available in the container for future use. Typically, the dose indicating device has an indexing (i.e. counting) mechanism actuated by movement of the container relative to the housing, wherein a preset amount of relative movement results in a count being indexed.
U.S. Pat. No. 4,817,822 describes an aerosol dispenser having a dose indicating device which, in a first embodiment is removably attached to the end of the protruding portion of the aerosol container. The operating mechanism of the dose counter is located within a housing which extends from the end of the aerosol container along the external surface of the tubular housing.
U.S. Pat. No. 4,817,822 describes a dispenser having a dose indicating device in which the operating mechanism of the dose indicating device is located within a compartment in the housing and is actuated by means of an actuator member attached to the aerosol container.
W096/16686 describes an aerosol dispenser wherein the operating mechanism of the dose indicating device is electronic and wherein the actuating member comprises a microswitch set into the wall of the housing. The electronic counting mechanism and microswitch are contained within a hermetically sealed enclosure.
U.S. Pat. No. 5,482,030 describes an aerosol dispenser having a mechanical dose indicator device located in and connected to the housing in the vicinity of the outlet tube of the aerosol container when fitted.
Many different pharmaceutical products are sold in the form of aerosol containers requiring different sized container bodies and/or valves according to the required specifications. It is therefore normal for there to be dimensional variations between different aerosol containers. Even between the same products the re can be dimensional variations due to manufacturing tolerances.
A problem which is common to all of the dose indicating devices discussed above is that the indexing mechanism, which is actuated by relative movement between the container body and housing, lacks any means of compensating for dimensional variations between different aerosol containers. Hence, the indexing mechanisms must be dimensioned according to the product with which they are to be used, and so will not be interchangeable with other products. Furthermore, in order for the indexing mechanism to record a count accurately, the dimensions of the components of any particular device must be manufactured to the required high tolerances.
The Applicants have now found that this problem can be ameliorated by use of a coupling element which compensates for excess movement (i.e. overtravel) of the container relative to the housing. By excess movement herein it is meant movement greater than that required to index a count. In one aspect, such excess movement is related to dimensional variations in the container and other parts of the dispenser.
According to one aspect of the present invention there is provided a dispenser comprising a housing having a support; a container, locatable within said housing, having an outlet, wherein said container dispenses through said outlet in response to movement of the container relative to the housing; and an actuation indicator having an indexing mechanism actuatable by movement of the container relative to the housing, wherein the indexing mechanism includes a coupling element to compensate for excess movement of the container relative to the housing.
By use of coupling element, such as a lost motion coupling, it is possible to create an actuation indicator of one size which can be used in dispensers having valves and actuators made within a wide range of manufacturing tolerances and can even fit a range of valves and actuators made to different dimensions.
Suitably, the indexing mechanism is actuatable by a predetermined movement of the container relative to the housing.
Suitably, the indexing mechanism indexes actuation by means of a predetermined rotary movement of a first member driven by movement relative to a second member during actuation of the dispenser. Preferably, the second member remains stationary relative to the housing during actuation of the dispenser.
In one preferred aspect, the first member comprises a pinion carried by a shaft through the coupling element and the second member comprises a rack.
In another preferred aspect, the first member comprises a yoke for engagement with the second member through the coupling element.
Suitably, the coupling element comprises a friction drive mechanism.
Suitably, the container is an aerosol container.
Suitably, the container provides measured doses. Preferably, the actuation indicator indicates the number of doses dispensed from or remaining in the container.
Suitably, the dispenser herein comprises a housing having a support; a container, locatable within said housing, having an outlet member, wherein said container is movable relative to the housing to enable dispensing therefrom and said outlet member is connectable with said support to prevent relative movement therebetween; and an actuation indicator, locatable within said housing. Preferably, the container and actuation indicator are reversably removable from the housing as a single unit.
Suitably, the actuation indicator is engagable with the container in the vicinity of the outlet member. More preferably, the actuation indicator is engagable with the outlet member.
Suitably, the actuation indicator is provided with a grip member which is engagable with a neck portion of the container. Preferably, the neck portion is adjacent to or on the outlet member.
Suitably, the housing is provided with an outlet, more preferably in the form of a mouthpiece. Preferably, the dispenser comprises a passage through which dispensed doses may pass from the container to the outlet.
Suitably, the dispenser is a breath operated inhaler which is actuable in response to the inward breath of a user.
Preferably, the dispenser herein is an aerosol dispenser comprising a housing in which a container is removably located, an outlet leading from the housing and a support in the housing arranged to receive an outlet member of the container and having a passage through which the contents of the container may pass to the outlet, the outlet member being held stationary in the housing support and the body of the container being moveable relative to the outlet and housing to dispense its contents in measured doses, and an actuation indicating device having an actuation indicator for indicating the number of doses dispensed from or remaining in the container. More preferably, the actuation indicating device is tightly connected to the container in the vicinity of the outlet member, such that the container and actuation indicating device may be removed from the housing as a single unit.
Preferably, the dispenser herein is a metered dose inhaler comprising a housing in which the container is removably located, an outlet leading from the housing, a support in the housing arranged to receive the outlet member of the container and having a passage through which the contents of the container may pass to the outlet, the outlet member being held stationary in the housing support and the body of the container being movable relative to the outlet and housing to dispense its contents in measured doses, and a window through which the actuation indicator may be viewed.